Machinery can accelerate a mass due to a centralized force. Some designs were developed in the Industrial Revolution. Physics textbooks teach these principles. Countless thousands of designs are used every day. Other accelerating motions can also induce velocity to a mass, including gyrating structures. Fluids under pressure can accelerate a mass, a conventional sand-blaster being an example. Fluids as a class are covered in this broad area of mass acceleration.
Rotation of a mass generates radial acceleration. If any part of the rotating mass is separated from the rest of the rotating mass then the central force Is no longer a radial accelerator to the separated mass. Once separated the mass follows a trajectory based upon whatever forces are still applicable, air resistance is a candidate for classic atmospheric projectiles. At the moment of separation from the radial force the separated mass' instantaneous velocity is tangent with respect to the radial force.
In introductory physics classes students are taught this concept using the ‘string with a ball’ wherein an undefined mechanism ‘cuts’ the string (a teaching construct). At the moment the ball is separated from the radial force an initial tangential motion for the ball is defined. Impact and atmospheric induced losses and gravity will dominate the changes in position, velocity, and acceleration of the ball until the ball comes to rest. The initial velocity of the ball attached at the end of the string most distant from the central force, axis of rotation, is simply the circumference of the pathway times the frequency of the rotation. For example if the string length is 3 feet (neglecting the dimensions of the ball) and is completing 10 rotations per second (10 Hz) then the instantaneous velocity is 3π time the frequency ‘10’. (3)*(3.14)*(10)=94.2 feet per second.
The string can be replaced with a hollow tube, and the mass can be any object that fits inside the hollow tube. The classic experiment is to have a latching mechanism holding the mass at some arbitrary location (initially at the most distant location from the axis of rotation) inside the hollow tube until the hollow tube, latch and mass are rotating at the desired frequency. Once at a stable frequency the latch releases the mass and the mass moves away on a trajectory defined as the tangent (instantaneous) from the axis of rotation. This experiment is nearly identical to the ball on a string experiment.
If the latched mass' position is moved inward toward the axis of rotation the mass will be released onto the inner surface of the hollow tube. Since the hollow tube is under a radial force there wilt be forces Imparted onto the mass.
Equations of motion, at the most simple level, can provide sufficient estimates of performance of a radial force's impact on a mass' exit velocity, given an arbitrary starting location inside the hollow tube. Along the inner surface of the hollow tube, where the mass is located, instantaneous velocity and radial acceleration vectors can be defined. If the hollow tube is considered to be made from an infinite number of thin rings then the velocity and acceleration of the tube's most distant ‘thin ring’ are greater than those ‘thin rings’ closer to the axis of rotation.
Sliding friction is nominally parts per thousand of the effective normal force on the mass inside the hollow tube. Rolling friction is typically smaller than sliding friction. Air resistance is also small as the local air mass Inside the rotating structure is accelerated in the same manner due to collisions between the inner surface of the hollow tube and the local air mass. Minor changes in the frequency are occurring as well. Causes of frequency changes include a variable mass distribution and drive power fluctuations.
As the mass is thrown from the rotating reference frame to a non-rotating frame there will foe an energy loss associated with the first physical contact. Depending upon the transition mechanics (physics sense) the mass can ‘smoothly’ traverse onto the non-rotating frame, or recoil upon first contact. Recoil would result in the mass changing trajectory from the nominal ‘tangent’ (at the moment of separation from the rotating system) to a new trajectory.
Cutting and abrasion can occur when one mass interacts with another mass. Both masses can be moving hut more traditional concepts are defined as one stationary mass being impacted by a second moving mass.
Methods exist for some of the applications Including using pneumatic, hydraulic, pneudralic, chemical, coiled (stored) energy, and gyrating methods of accelerating a mass which applies force on an object upon impact. For example, rotating machinery is used to throw shot-blast mass in a non-discriminating pattern or for cleaning castings in a foundry.
Sand-blasting uses a series of complicated relationships to perform abrasion. The stationary mass is secured, to prevent the abrasion mass torn causing the stationary mass from moving—conservation laws. Sand and air are mixed. Gas pressure causes the local air to move from the higher pressure zone to a lower pressure zone, generating a flow of air over a mass of small sand particles. These small sand particles become airborne and join the moving mass of air, thus creating a combined air/sand mixture. The moving air and sand are directed at the stationary mass, causing impacts (abrasion). If the mass of the non-air objects (stone instead of sand) are too large to be captured in the air flow then only air will impact the stationary mass.
Extremely high velocity water can cut harder surfaces such as metals. High pressure systems force water through a small exit opening.
Cutting tools can also use an accelerated mass. Chain saws are commonly used, wherein the metal cutting teeth are moved by a rotating shaft. Non-circular motion of the cutting teeth is defined by the pathway constraining the motion of the chain attached to the cutting teeth. Circular Saws, where the blade is directly attached to the rotating motor, also reflect state-of-the art.
Numerous chemical spray coating devices are sold ail over the world. Some devices offer combined chemicals as part of their delivery system. Nominally pressurized containers are used to move the sprayed chemicals. Once the pressurized gas is expended the application of the chemical is stopped. Pumps can supply pressurized systems with the necessary pressurized gas to keep the chemical delivery nearly continuous.